Effect Of Functional PVA Microspheres And Fiber On The Properties Of Thermoplastic Starch

With the improvement of people to the requirements of environmental protection, environment-friendly biodegradable materials have been paid more and more attention. Thermoplastic starch(TPS), prepared by plasticized starch, which is considered the most development prospects biodegradable plastic, has the advantages of thermoplastic processing, low cost and so on. However, bad water resistance and poor mechanical properties limit the starch plastics applications. Polyvinyl alcohol(PVA) is a kind of synthetic biodegradable polymer with excellent performance, which contains a large number of hydroxyl groups in the molecular chain. It has high mechanical strength and toughness, to better compensate for the lack of full-starch material properties.This paper is starting from the different forms of PVA. With glutaraldehyde as crosslinking agent, polyvinyl alcohol microspheres(PVAMS) were prepared by the condensation reaction of aldehyde with the hydroxyl. And studied the influence PVAMS and polyvinyl alcohol fiber(PVAF) thermoplastic starch, respectively. Then using anhydride modified PVA microspheres and fiber, so as to introduce carboxyl groups on their surface, and as a crosslinking point when they melt blended with thermoplastic starch, in order to better improve the overall performance of the thermoplastic starch.(1) PVAMS was modified by using maleic anhydride, succinic anhydride, citraconic anhydride and itaconic anhydride, respectively. Research of different SAA modified degree and different amount of PVAMS on the properties of thermoplastic starch composites. The results showed that, PVAMS and modified PVAMS can better improve the mechanical properties and thermal stability of composites, reduced water absorption. When the mass ratio between SAA and PVAMS is 20wt%, SAA-PVAMS(PVAMS modified by SAA) content was 1wt%, the tensile strength, elongation at break and impact strength of PVAMS/TPS composites were up to 5.35 MPa, 76.86% and 5.35 KJ/m2, respectively. With respect to the TPS, PVAMS/TPS more difficult to process, and with the increase PVAMS content, its mobility gradually deteriorated.(2) PVA fiber(PVAF) was modified by using MA, SAA, CTA and ITA, respectively. Then, PVAF and modified PVAF reinforced thermoplastic starch(TPS) were prepared. Research the types of anhydrides, and the mass ratio between PVAF and anhydride on the properties of composite materials. The results showed that 20 wt% SAA modified PVAF have the best effects on performance of thermoplastic starch. And when SAA-PVAF(PVAF modified by SAA) content was 1.5wt%, the tensile strength, elongation at break and impact strength of PVAMS/TPS composites were up to 6.68 MPa, 83.57% and 38.82 KJ/m2, respectively. Compared to PVAMS/TPS, PVAF/TPS were more difficult to process.(3) In the system which the mass ratio between starch and glycerol was 3:1, and PVAF content was 1.5wt% of the total Mass, thermoplastic starch plastics were prepared with different content of PVAMS. The effects of the unmodified PVAMS/ the unmodified PVAF and SAA-PVAMS/ SAA-PVAF on the properties of composite materials were studied. Compared with the PVAMS/PVAF without modification, PVAF and PVAMS after SAA modification, carboxyl groups can be introduced on their surface, increase the interface adhesion strength between SAA-PVAMS/PVAF and starch matrix, thereby the performance of the material is well improved. With the increase of the content of the microspheres and fiber system, tensile strength and impact strength of the material first increases and then decreases, elongation at break, water resistance and processing properties decreased. And when SAA-PVAMS content was 1.5wt%, the tensile strength of SAA-PVAMS/SAA-PVAF/TPS was the best of 6.48 MPa.